tim marrs engine tuning illustration
Tim Marrs

Whether basic bolt-ons or forced-induction, gearheads can’t help but modify their rides. With the rise of handheld and PC-based ECU tuners, folks have an easier time than ever making big power from home. But don’t let the approachability of these devices fool you, as simple mistakes that could ultimately destroy your engine. For some insight and advice, Road & Track sat down with industry leaders to discuss the current state of engine software tuning.

Before most folks get to tweaking the software controlling their engines, upgraded hardware of all kinds often joins the mix; don’t expect to make reliable power if the components within an engine aren’t up to task. According to Lingenfelter Performance Engineering calibration engineer Christian de Saint Preux, a healthy engine that’s been well maintained is an absolute must before beginning the tuning process. Ensure there are no active oil or fuel leaks and that the no components are overly worn. Replacing worn components is a must, but avoid purchasing replacement parts that are just barely certified to meet your output goals. Have a good idea of your project’s endpoint before you start throwing parts at it.

lingenfelter performance engineering engine build dirk stratton
Lingenfelter Performance Engineering

“The package needs to be well sorted out before the calibration process,” Saint Preux told R&T. “That includes ensuring it's not a badly maintained motor. If the mechanical side of it isn’t 100 percent, the calibration won’t be 100 percent either.”

Once you have an idea of where you’d like the project to go, the next step is to select the type of fuel you intend to run in the car. According to AEM Performance Electronics engineer John Concialdi, the fuel type will ultimately dictate everything you do down the line in the tuning process.

“When I was building race engines for people my first question always was what type of fuel do you plan to run,” Concialdi said. “You build your engine around the fuel type before you do anything else.”

The reason for choosing your fuel type first is rather simple. All tuning is based around the exact same set of factors: Every internal combustion engine needs air, fuel, and an ignition source to run. The type of fuel you choose to run through that engine impacts the whole system, and changes the parameters required to make the engine run effectively. An engine that’s been set-up to run on 87 octane simply won’t utilize the same cam timing, ignition timing, air-fuel ratio or compression ratio as one set to run on 118 octane fuel. This same concept applies for modern and classic engines alike.

“Tuning is tuning,” Concialdi said. “The physical requirements of an engine remain the same, regardless if it’s a carbureted or a fuel-injection system. It’s just that the method of achieving correct or incorrect tuning is different. You can blow your engine up with a lot more precision with an EFI system than a carburetor.”

lingenfelter performance engineering dirk stratton corvette
Lingenfelter Performance Engineering

Before you try to tune anything within the ECU, you need to start learning about what engines need to make more power. Study the basics: air-fuel ratio, ignition timing, compression ratios, ignition phasing and camshaft phasing are a great place to start. There are many great books available on the basics of engine tuning, which cost far less than a blown engine. That said, nothing can match the skills learned through proper instruction, according to Saint Preux. There are tuning courses available for those who want to learn more about the basics, but experience is an inevitable part of honing the craft.

Regardless of which route you take, learn how these different engine inputs impact one another, and spend time trying to understand what areas your specific engine needs. Get to know where these values sit in stock form, and keep that in mind as a baseline to reference as you move forward. You also must learn where the Top Dead Center of your engine is, as all your tuning parameters are based off of this position. Most modern engines don’t feature any timing pointers, with both Concialdi and Saint Preux suggesting you mark the positions for your engine’s safety.

The most common mistake people make relates to setting the engine's timing. More specifically, people routinely blow their engines up by giving the engine too much timing. Unfortunately it’s an easy trap to fall into for new tuners, as the gains on paper look very promising. Do not ignore this warning.

lingenfelter performance engineering cadillac atsv
Lingenfelter Performance Engineering

“I’ve been a victim of that once,” said Concialdi. “One of my engineers, who is no longer an engineer here, blew my NSX’s engine up. He told me that he found me 30 horsepower, and what he really gave me was a five cylinder engine. He put so much timing in it that it holed a piston.”

Another common mistake that people make comes in the form of running the engine too lean. This happens when the air-fuel ratio within the cylinder doesn’t contain enough fuel, which in turn raises the temperatures within the cylinder. High temps are bad for everything from your pistons to your spark plugs, and can cause serious damage. Saint Preux further noted that idle operation is another area that new tuners tend to struggle with, and is a key sign of an improper calibration.

Once you’ve established a baseline engine fitness and which fuel type you’re running, you’ll need to decide which method you plan to use to modify the engine-management software. Handheld tuners are incredibly simple to use and rather cost effective, but they do lack some of the fine-tuning adjustments and data logging capabilities of a dedicated PC tuner. Handhelds do allow access to a world of pre-written tunes, many of which come from reputable aftermarket companies. Often these tunes are designed to be used with a specific set of parts detailed by the company, which helps keep the tuning parameters consistent from one car to another. These companies also have to do some form of validation and reliability testing in order to be verified for sale in states like California, which is a good thing for customers everywhere. Concialdi believes that as long as you go through a trusted vendor and follow their instructions, the chances of hurting your engine with a pre-written tune are low.

That said, Concialdi adamantly opposes the idea of downloading a tune from your favorite forum. While someone might be able to make incredible claims about how they doubled the output of their stock vehicle, there are simply too many small factors that can lead to catastrophe when tuning.

lingenfelter performance engineering dyno room
Lingenfelter Performance Engineering

“They don’t have a dog in the fight when they’re just tossing a tune out,” said Concialdi. “That dude doesn’t know jack about your engine, and has no clue about what you’ve done. At least if you get something from a reputable tuner, it will have been tested. Those tunes will say that they’re meant for a stock Subaru motor or what have you. So you’ll know the parameters.”

Data collection is another huge component to tuning a vehicle. While some handheld tuners do allow for basic data collection, a dedicated PC-based system can’t be beat. Whichever system you use, learning how to navigate the software before tuning is imperative. Plug the system into your car’s ECU to understand the system’s baseline. From there, practice navigating the software. These systems need input from the car to show anything meaningful, which means you won’t be able to learn much by operating it without a car plugged in. Part of collecting data also comes from repeatable testing, which is where a dyno comes in. Many home tuners are tempted to try and refine their setups on the street, but that simply isn’t a great option. Most tuning is done with data collected by taking an engine to speeds well beyond 100 mph. Doing triple-digit speeds on the road may land you in jail, whereas in a dyno shop you can pay attention to the vital information coming back at you. If you’re going to try and tune a car, budget for that dyno time.

If you already have an older aftermarket ECU in your project car, the age of that system might be a limiting factor today. Companies like AEM consistently end customer support for outdated or aging models. If you have an issue with a part they can’t source or repair, you’re going to be in the market for a new ECU regardless. This is an area worth addressing before you start trying to dig into the software.

lingenfelter performance engineering dyno room
Lingenfelter Performance Engineering

Tuning a vehicle is genuinely complicated. That’s a huge reason why companies like Lingenfelter have been in business for more than five decades. That said, it isn’t an impossible skill to learn. Whether or not you should tune your own vehicle will largely come down to what your personal skill level is, and how much time you’re willing to invest in the craft. Saint Preux notes that folks often believe a tune can be written in a matter of hours. That might be true if you’re a trained professional, but you likely aren’t. That doesn’t mean you shouldn’t try and learn, but keep realistic expectations in mind. Search for help if you need it, and don’t push your engine within an inch of its life. With that attitude, you have a shot of building a powerful and reliable engine, along with the satisfaction that comes from doing it yourself.